A so-called Non-ZIF (Zero Insertion Force) connector is known as an example of an FPC connector in which an insertion force is necessary when a FPC is inserted into the connector.
A Non-ZIF type of FPC connector generally has a structure in which an insertion and retaining of an FPC is carried out in a single action, so that by setting a distance (space) between a pair of contacts (or a distance (space) between a pair of contact pieces provided in a single contact) to be slightly narrower (smaller) than the thickness of the FPC, upon an FPC being inserted into the pair of contacts, a predetermined amount of contacting pressure is applied from the pair of contacts (contact pieces) to the FPC, whereby the FPC and the contacts connect to each other. However, since the inserted FPC is only retained by the contacting pressure of the contacts (contact pieces), if an unintentional strong external force is applied on the FPC in a pulling-out (removal) direction, the FPC can come out of the contacts unexpectedly.
On the other hand, in a ZIF type (in which an insertion resistance between the FPC and the contacts does not occur when the FPC is inserted) of FPC connector having an actuator, since the contacting pressure between the contacts (contact pieces) and the FPC can be increased by operating the actuator in a locking direction, the FPC can be effectively prevented from being unintentionally pulled out from the connector.
Hence, the applicant of the present invention produced the FPC connector disclosed in Japanese Unexamined Patent Application No. 2009-205914.
The FPC connector of the above-mentioned Japanese Unexamined Patent Application No. 2009-205914 is provided with an insulator having an FPC insertion groove into which an FPC having (a pair of) locking portions on the side edges thereof, respectively, is removably insertable; a plurality of contacts supported by the insulator such that the contacts are electrically connected with a circuit board; a single lock member having a pair of lock claws that are disengageably engaged with the pair of locking portions, respectively, the single lock member being supported by the insulator to be rotatable between a locked position, at which the pair of lock claws respectively face the locking portions in the FPC removing/insertion direction, and an unlocked position, at which the pair of lock claws do not face the locking portions in the FPC removing/insertion direction; and a pair of compression coil springs which rotatably bias the lock member toward the locked position.
Upon the end of the FPC being inserted into the insulator, the lock member, which was positioned at the locked position, is rotated to the unlocked position by the lock claws being pushed by the end of the FPC. Furthermore, when the lock claws no longer face the locking portions, the lock member automatically rotates to the locked position by the biasing force of the compression coil springs, and the lock claws become engageable (lockable) with the locking portions.
Accordingly, the FPC connector of the above-mentioned Japanese Unexamined Patent Application No. 2009-205914, while being a type in which a Non-ZIF and an actuator are provided, can connect a FPC with a contact via a single action of inserting the FPC into the insulator.
In the FPC connector of the above-mentioned Japanese Unexamined Patent Application No. 2009-205914, since a compression coil spring is provided on each of the left and right sides of the insulator and the biasing force of each compression coil spring is utilized to rotatably bias the lock member toward the locked position, if the axial length of the compression coil springs is made long (if the compression coil springs are made to deform easily), the lock member can be rotated by a large amount with a small amount of force. However, if the connector is made thinner so as to have a low profile, it becomes difficult to rotate the lock member by a large amount with a small amount of force since the axial length of the compression coil springs becomes shorter (since the compression coil springs become more difficult to deform).
Furthermore, since the FPC insertion grooves and the attachment region of the compression coil springs of the insulator are at different positions from each other in the width direction (arrangement direction of the contacts) of the insulator (FPC), the size of the insulator (and the connector) easily increases in the arrangement direction of the contacts.
Furthermore, since two lock claws are provided on one lock member, if an unintentional external force is applied to the lock member in a locked state, the lock member that was positioned at the locked position unintentionally rotates to the unlocked position, so that both of the lock claws no longer face the respective locking portions.
Therefore, there is room for improvement in regard to the lock retention against unintentional external forces.